Inhibition of A-amylase in vitro and in vivo hypoglycemic effect of methanol extract of Alchemilla viridiflora Rothm

Abstract

Dry methanol extract (DER 3.95:1) of aerial flowering parts of Alchemilla viridiflora Rothm., Rosaceae, obtained after successive extraction with cyclohexane and dichloromethane, predominantly contains polyphenols, tannins (3.74%), mostly ellagic, and flavonoids (0.30%), hexosides of quercetin and kaempferol. It shows ACE inhibitory and anti-Helicobacter pylori activity in vitro (1). Based on the traditional use of the common A. vulgaris in the treatment of diabetes (2), the effect of this A. viridiflora extract on α-amylase activity in vitro and lowering blood glucose in rats were investigated. α-Amylase inhibitory activity was assessed using the 3,5-dinitrosalicylic acid method. Extract in doses of 50, 100 and 200 mg/kg, p.o., was administered to streptozotocin-induced diabetic rats for 20 days, and blood glucose level and weight of rats were monitored during treatment. Extract inhibited α-amylase activity at IC 50 5.47 ± 0.30 mg/mL. A dose of 200 mg/kg significantly decreased blood glucose level after 10 (32.2%) and 20 days of treatment (38.3%). The effect of this dose was similar to the effect of the reference drug, glibenclamide. A dose of 100 mg/kg significantly increased glucose level by day 10 (50.5%) and a reduction in blood sugar level of 51.2% was observed only after 10 days. Body weight was correlated with changes in blood sugar levels. A dose of 50 mg/kg had no statistically significant effect. Results indicate a significant potential of A. viridiflora aerial parts in the treatment of diabetes, which must be confirmed by additional studies, and active ingredients need to be identified.

Suvi metanolni ekstrakt (DER 3,95:1) nadzemnih delova u cvetu Alchemilla viridiflora Rothm., Rosaceae, dobijen nakon sukcesivne ekstrakcije cikloheksanom i dihlormetanom, sadrži visok nivo polifenola, tanina (3,74%), uglavnom elagnih, i flavonoida (0,30%), heksozida kvercetina i kemferola. Pokazuje ACE inhibitornu i anti-Helicobacter pylori aktivnost in vitro (1). Na osnovu podataka o tradicionalnoj upotrebi herbe A. vulgaris, najčešće korišćene Alchemilla vrste, u lečenju dijabetesa (2), ispitivan je uticaj navedenog ekstrakta A. viridiflora na aktivnost α-amilaze in vitro i na snižavanje nivoa glukoze u krvi kod pacova. Uticaj na aktivnost α-amilaze procenjen je primenom metode sa 3,5- dinitrosalicilnom kiselinom. Ekstrakt A. viridiflora u dozama od 50, 100 i 200 mg/kg, p.o., aplikovan je pacovima sa dijabetesom izazvanim streptozotocinom tokom 20 dana, a nivoi glukoze u krvi i težina pacova su praćeni u određenim vremenskim intervalima tokom trajanja tretmana. Ekstrakt je inhibirao aktivnost α-amilaze, a vrednost IC 50 iznosila je 5,47±0,30 mg/mL. Doza od 200 mg/kg značajno je smanjila nivo glukoze u krvi nakon 10 (32,2%) i 20 dana tretmana (38,3%). Efekat ove doze bio je sličan efektu referentnog leka, glibenklamida. S druge strane, doza od 100 mg/kg značajno je povećala nivo glukoze do 10. dana (50,5%) a do značajnog poboljšanja, tj. sniženja nivoa šećera od 51,2% dovela je tek nakon 10 dana. Telesna težina bila je u korelaciji sa promenama nivoa šećera u krvi. Doza od 50 mg/kg nije imala statistički značajan efekat. Rezultati ukazuju na značajan potencijal herbe A. viridiflora u lečenju dijabetesa, što mora biti potvrđeno dodatnim studijama, a aktivni sastojci identifikovani.